1. The Field of the Invention
This invention is generally related to conveyor belt structures. In particular, the invention is related to an apparatus for enclosing and supporting belt conveyor systems.
2. Background of the Invention
Conveyor belts are widely used for moving various types of material from one location to another. In its simplest form, a conveyor belt is comprised of a flat belt secured end to end so as to form an elongated loop. This loop of belting is then passed around a pair of rollers located at either end of the elongated loop of belting. Intermediate between the ends of the loop may be disposed supporting rollers, plates, or similar support structures. The belt is then caused to rotate by an attached motor or other power source. Thus, material may be placed upon the belt at one end and carried to the opposite end of the belt, where it is either removed or caused to fall from the belt as the belt carrying the material passes around the end roller and begins its return to its original position.
Certain slightly more complex configurations of the traditional conveyor have also been developed. One such configuration is the formation of a trough on the upper surface of the belt which carries material. This may be done by using a flexible belt which rests on a plurality of rollers disposed in a generally semicircular configuration to form a trough.
One fairly typical type of trough conveyor employs a central roller which lies in a generally horizontal plane. On either side of the central roller are side rollers which are disposed at an approximately 35.degree. angle above the horizontal plane. The flexible belt then rests on the upper surfaces of the three rollers. This causes the belt to form a trough as generally described above. As the belt returns to its original position it generally passes under the rollers forming the trough and simply rests on a return idler which lies in a generally horizontal plane below the trough.
This type of roller and belt configuration is particularly useful when conveying particulate bulk materials. It will be appreciated that such a belt configuration keeps such materials confined on the belt surface. In addition, such systems are flexible in design so that specifically configured troughs may be formed for specific types of materials.
Conveyor belts of the type described above have received wide acceptance in the transportation of many types of materials. Such materials may include packages and large containers which may be transported on a simple flat belt system. As discussed above, other materials such as particulate materials may be conveyed on a belt generally forming a trough configuration. Such materials may vary from powders to large aggregate materials. Materials which are conventionally conveyed by conveyor belts include coal and other mining products, gravel, cement, chemical feedstocks and food products (including grains and the like).
Some obvious problems develop when using conveyor belts to convey particulate materials of the type described above. For example, if the conveyor belt runs out-of-doors, it is difficult to protect the conveyed material from the elements. A significant loss of material may result from wind blowing across the surface of the conveyor belt. In addition, the elements, including rain and snow, may damage or destroy certain products as those products are moved on the conveyor.
With the advent of strict air quality standards, it also becomes necessary for industrial plants of all types to be concerned about particulate pollutants in the atmosphere adjacent the plant. Traditionally, one major source of particulate pollutants has been exposed conveyor belts carrying particulate material. For example, electric power plants generally move coal by conveyor to supply coal fire furnaces. However, wind blowing across an open conveyor could cause serious air pollution problems by causing coal dust to enter the air. As a result, the Environment Protection Agency and various related state agencies now generally require that particulates being moved along a conveyor system be contained or covered in some manner.
In order to solve the problems which have been encountered in the use of open conveyors, various systems have been devised to cover some or all of the conveyor. In particular, two general kinds of enclosures have been developed. These include partial enclosures and total enclosures.
Generally, a partial conveyor enclosure comprises some apparatus for shielding the conveyor from rain and snow. Such partial enclosures generally include a cover over the top of the conveyor. In the case of partial enclosures, however, the sides of the conveyor are left exposed to the elements.
As a result of the open sides of partially enclosed conveyor systems, these systems are not particularly satisfactory for use in conveying fine particulate material. As briefly discussed above, such material can be carried away by wind blowing across the top of the conveyor surface. As a result, these systems are generally inadequate for the purpose of controlling particulate pollutants.
The second type of conveyor enclosure is a total enclosure where, in essence, a structure is constructed which totally surrounds the belt conveyor system. Typically, such total enclosures are constructed of high quality steel molded into a generally circular tube. The conveyor belt is then disposed within and totally surrounded by the tube.
Several problems have developed in the use of such conventional total conveyor enclosures. One problem is that it is extremely difficult to service the interior of such a conveyor system. Obviously, when the conveyor is totally enclosed in a tube, problems in servicing the conveyor are acute because of the limited access to the interior of the tube.
Another severe problem with total enclosures is that they are extremely expensive. Such enclosures are expensive to manufacture in that they require the use of expensive materials and expensive fabrication techniques. In particular, fabrication of conventional conveyor enclosures is extremely labor intensive. For example, it is not uncommon for fabrication of a forty foot section of such a conveyor to consume significantly more than sixty-five man hours. In addition, total enclosures are difficult to ship. They are generally extremely large and bulky and as a result, generally only a limited length of such conveyor enclosure can be shipped on a single semitrailer or railroad car. It is also difficult to stack multiple lengths of such an enclosure for shipping.
A further problem with conventional conveyor systems is that they have a limited span. In order to span large distances, it is necessary to construct expensive and complicated support mechanisms. Such support mechanisms make large spans of such conveyor systems extremely expensive.
Hence, what is needed in the art are methods and apparatus for partially or totally enclosing conveyor belts which overcome the problems discussed above. In particular, it would be a significant advancement in the art if a conveyor system were produced which was easily manufactured, preferably employing conventional and readily available parts and materials. It would also be an advancement in the art if such apparatus could be produced which was inexpensive to ship and was capable of being shipped while stacked on pallets, or in the same manner as conventional piping. It would also be an advancement in the art if such a system could be produced which was easy and inexpensive to assemble. Furthermore, it would be an advancement in the art if such a conveyor system could be produced which allowed the conveyor to be totally enclosed, yet was easy to access and service. It would be a further advancement in the art if such a conveyor system could be produced which was capable of being placed into long spans using conventional and inexpensive technology and equipment. Such methods and apparatus are disclosed and claimed herein.